Enhanced electric field-induced strain and electrostrictive response of lead-free BaTiO3-modified Bi0.5(Na0.80K0.20)0.5TiO3 piezoelectric ceramics

Lead-free (1-x)Bi0.5(Na0.80K0.20)0.5TiO3-xBaTiO3 or (1-x)BNKT-xBT (x = 0 – 0.15 mol fraction) piezoelectric ceramics have been investigated. The optimum density was found for the ceramic sintered at 1125°C, corresponding 98 – 99% of their theoretical values. All ceramics had a single perovskite structure. The coexisting mixed tetragonal-rhombohedral phases all over the entire compositional range with tetragonal phase becoming superior at higher BT. The diffuse phase transition was promoted by the addition of BT. With increasing BT content, the Tm and Td values were found to decrease. Phase transition from ferroelectric (FE) phase to ergodic relaxor (ER) phase was also induced by the changes in BT content. These changes significantly suspended long-range ferroelectric order, then correspondingly reducing the Pr and Ec, resulting in an improvement of electrostrictive and electric field-induced strain responses. A significant increasing of electric field-induced strain response (Smax = 0.37% and d*33 = 630 pm/V) is noted for the x = 0.05 ceramic. Furthermore, high electrostrictive coefficient (Q33) of 0.0421 m4/C2 is observed for this composition, which was more than ~ 2 times (~108%) as compared to the pure BNKT ceramic. The studied results indicated these ceramics can be considered promising candidates for actuator applications

Enhanced electrical and energy harvesting performances of lead-free BMT modified BNT piezoelectric ceramics

Lead-free (1-x) (Bi0.5Na0.5)TiO3-xBi(Mg0.5Ti0.5)O3 or (1-x)BNT-xBMT (x = 0–0.20) piezoelectric ceramics have been investigated for phase evolution, microstructure, dielectric, ferroelectric, piezoelectric, electric field-induced strain, energy storage density, energy harvesting, and magnetic properties. All compositions exhibited high density sintered ceramics (~ 6.13–6.30 g/cm3). With increasing modifier content, the crystal structure changed from rhombohedral to cubic phase. When BMT content was added, the grain size and Tm were found to increase. The x = 0.05 ceramic showed good piezoelectric (low-field d33 = 159 pC/N) and ferroelectric (Pr = 23.84 µC/cm2, Ec = 34.41 kV/cm) properties. The BMT additive also produced an improvement in electric field-induced strain, energy storage efficiency, and magnetic properties. The highest piezoelectric voltage constant (g33 = 26.29 × 10−3 Vm/N) and the off-resonance figure of merit (FoM) for energy harvesting (~ 4.18 pm2/N) were also obtained for the x = 0.05 ceramic, which was ~ 3.4 times (240%) as compared to the pure BNT ceramic. This suggested that the ceramic has a potential to be one of the promising lead-free piezoelectric candidates for further use in piezoelectric energy harvesting applications

Influence of Al2O3 Nanoparticles’ Incorporation on the Structure and Electrical Properties of Pb0.88Sr0.12Zr0.54Ti0.44Sb0.02O3 Ceramics

In this research, the effects of an Al2O3 nanoparticle additive on the structure and electrical properties of Pb0.88Sr0.12Zr0.54Ti0.44Sb0.02O3 (PSZST) ceramics were investi‐ gated. The PSZST ceramics with the addition of 0 - 2.0 vol % Al2O3 were fabricated via a solid-state mixed oxide method and sintering at 1250°C for 2 h to obtain dense ceramics. X-ray diffraction indicated that all compositions exhibited a single perovskite structure. Phase identification showed coexisting mixed rhombohedral and tetragonal phases for the modified ceramics, while the unmodified ceramics showed a rhombohedral-rich phase. The addition of Al2O3 nanoparticles was also found to improve the densification and the electrical properties of the PSZST ceramics, such as dielectric constant and polarization. The 2.0 vol% sample showed the highest low-field piezoelectric coefficient (d33) value of 646 pC/N, which was 90% higher than that of the unmodified sample, suggesting that this composition had the potential to be one of the promising piezoelectric ceramic candidates for further use in actual applications

Energy harvesting, electrical, and magnetic properties of potassium bismuth titanate-based lead-free ceramics

In this research, the properties of bismuth potassium titanate modified by bismuth nickel titanate ceramics were investigated. XRD showed that all samples exhibited a single perovskite structure. The crystal structure changed from a tetragonal to a cubic phase with increasing modifier content. Average grain size decreased while the bulk density and hardness increased with the modifier. The improvement of mechanical properties was related to the change in microstructural and density. The 5– 10 mol% ceramics showed the good electrical properties. The maximum dielectric properties (ε′ = 1763, tan δ = 0.0697) were obtained for the 10 mol% ceramic. The highest piezoelectric voltage constant (g33 = 23.92 × 10−3 Vm/N) and the off-resonance figure of merit (FoM) for energy harvesting (~ 6.64 pm2/N) were obtained for the 5 mol% ceramic, which was more than 5.0 times (or 399%) as compared to the pure BKT ceramic. The additive also produced an improvement in the magnetization-magnetic field hysteresis loop. The obtained results suggested that the additive not only enhanced the mechanical properties but also improved the magnetic, and energy harvesting performances of the studied ceramics